(Topic ID: 243319)

Harlem Globetrotters- no MPU flashes

By pindude80

5 years ago


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  • 12 posts
  • 4 Pinsiders participating
  • Latest reply 5 years ago by pindude80
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#1 5 years ago

I just bought a HG last week. It worked when I picked it up and now that I set it up it won't boot; I don't get any flashes at the MPU. My friend and I tested all of the test points on the power driver board and they all have power. I am not getting 5v at either test points on the solenoid driver board or 5v at the test points on the MPU.

Any ideas on what I should check or test next?

#2 5 years ago

Check fuses at the rectifier board.

#3 5 years ago

I did a quick continuity check with them installed but can pull them to test better. If all of the rectifier board test points have voltage wouldn't that mean the fuses are good?

#4 5 years ago

Does the LED on the MPU turn on and stay on or does it never light? I'd suggest checking all of the connectors in the head, it sounds like one may have partially fallen off the board.

#5 5 years ago

Verify that J3 on the rectifier board is plugged in. Verify TP3 on the rectifier board is 12VDC. The solenoid driver board TP5 should read the same voltage as TP3 on the rectifier board.

If there's 12 volts DC at TP5 on the SDB, you should have 5 volts DC at TP1 if the 5 volt regulator is working.

When reporting back, let us know what the voltages were.

#6 5 years ago
Quoted from Eric_S:

Does the LED on the MPU turn on and stay on or does it never light? I'd suggest checking all of the connectors in the head, it sounds like one may have partially fallen off the board.

doesn't do anything. Since I just got this game I can't say for sure that the LED works. all of the connections are on properly and have been re-seated a couple times.

#7 5 years ago
Quoted from Billc479:

Verify that J3 on the rectifier board is plugged in. Verify TP3 on the rectifier board is 12VDC. The solenoid driver board TP5 should read the same voltage as TP3 on the rectifier board.
If there's 12 volts DC at TP5 on the SDB, you should have 5 volts DC at TP1 if the 5 volt regulator is working.
When reporting back, let us know what the voltages were.

I just checked the SDB voltages again. For some reason it's blowing fuse 3 and I'm not getting anything at TP3. I'm 99.9% sure we checked this before and we had the correct voltage; I want to say it was 14vdc. J3 on the rectifier board is plugged in. I have 6.4vdc at TP1 on SDB. TP2 was 265, TP3 was .5vdc, I didn't test TP4, TP5 was 47vdc

#8 5 years ago

I just checked the BR1,2, and3 on the PDB using this method I found on pinside and they all tested good: To test use Dmm in diode test. Put your neg blk lead to the pos DC point. Put red pos on either AC lug you should get around .4-.6v. Both AC lugs should read the same never move the black lead for this test. You just tested two diodes in bridge.
Now put red on the neg dc lug and black goes to each AC lead. Same thing as you just did .4-.6 should be read. Now you just tested the other two diodes. In the above info of the four readings nothing should be open. OL (over range) or shorted .1 or beep on metet.

#9 5 years ago

Fuse 3 goes to the bridge that supplies the 12 volts at test point 3. The 12 volts is changed to 5 volts at the SDB.
Since you're blowing the fuse, it sounds like the bridge went bad. With power off, you need to test the rectifier. Google how to test them - there's lots of guides.

#10 5 years ago

I just checked the 3 bridges as described in my post #8, it may not have been there when you were answering me, but all tested good.

#11 5 years ago

Just saw your post about testing the rectifier. Since you're blowing the fuse, something may have dropped between the back of the rectifier board and the chassis, causing the fuse to blow. I recommend removing the assembly and take a close look at it on a bench.

From experience - if the head is not bolted to the machine, and you remove the assembly, your head will tip quickly and violently, breaking other things in the head.

#12 5 years ago

I figured it out last night. I installed a new fuse, unplugged all of the connectors on the MPU board and powered up the game, the fuse didn't blow and I was getting the correct voltage at TP3 on the SDB. I then turned the game off, installed a connector on the MPU board, turned on the game, the fuse didn't blow. I did this until I got down to J4, plugged it in, turned on the game and the fuse below within a few seconds.

I pulled the MPU board. I did some continuity testing on the pins to make sure there wern't any solder bridges. I was getting ground on all 4 of the bottom pins which didn't seem right to how the trace routing looked on the board so I checked these pins on my Eight Ball Deluxe and only the bottom two pins had ground.

As it turns out, we fixed a few things on the MPU board and added a ground mod earlier in the day. The ground mod jumper wire insulation melted ever so slightly during install and was making contact with a leg of a resistor shorting it out causing my problem. I removed the ground mod wire, re-installed the mpu, and it booted right up! Next will be replacing all of the nasty looking pins on the bridge rectifier board.

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